This Mentored Clinical Scientist Development Award has been prepared for Jean A. Nemzek, DVM, MS. Dr. Nemzek is a boarded veterinary surgeon with a broad research background. After a fellowship in Comparative Medicine at University of Michigan, Dr. Nemzek joined the faculty in the Department of Pathology and the Unit for Laboratory Animal Medicine. This dynamic environment offers many experts in the field of inflammation and deep commitment to new investigators. Dr. Nemzek?s long-term research objective is to combine clinical experience and a solid basic science background to advance understanding of immune modulators in sepsis, organ failure, and acute lung injury. To achieve that goal, Dr. Nemzek is aligned with an exceptional mentor, Dr. Daniel G. Remick. They have outlined a career plan with the scientific, technical, and administrative principles necessary for independence as an investigator. The proposed studies examine the effects of sequential insults on inflammatory responses. It is theorized that sequential hits prime the immune system promoting synergistic response. This theory prompted several "two-hit" studies of inflammation. However, these studies have conflicting results, probably due to the diversity, timing, and compartmentalization of the insults given. The hypothesis of this study is that the enhanced mortality resulting after two inflammatory hits, septic peritonitis followed by acid aspiration, is mediated by an increased proinflammatory cytokine response produced at the site of the first hit. The first specific aim will determine if the exaggerated effect on lethality after two insults is due to increases in peritoneal inflammation with insults given at different intervals. The second specific aim will determine if a similar effect is seen when severity of the insults is increased. Together these aims will directly test the hypothesis and begin to identify cytokine mediators. The third specific aim will determine if the cytokine responses primarily localized to the peritoneal compartment and quantify cytokine production. Finally, cytokine profiles relative to the compartmentalization, timing, and severity of the hits will be used to determine if altering cytokine levels will reduce inflammation and lethality. This will confirm the role of specific cytokines in sequential inflammation. Successful completion of these aims could impact current two hit theories and use of immune therapy in septic patients exposed to additional inflammatory insults.